Rock Dust Could Help Fight Climate Change and Boost Crop Yields

A new Anglo-French study suggests that spreading crushed volcanic rock on farmland could help remove carbon dioxide from the atmosphere — and potentially boost crop yields. However, its effectiveness depends heavily on local soil conditions.

Researchers from Rothamsted Research (UK), INRAE (France), and the UK’s National Oceanography Centre tested basalt rock dust — a quarrying by-product — on two soil types: sandy and silty clay. In pot trials, they applied the dust at two rates (equivalent to 80 and 160 tonnes per hectare) and monitored changes in soil chemistry and ryegrass growth.

The method, known as enhanced weathering, accelerates the natural breakdown of silicate rocks, a process that draws CO₂ from the air and locks it into the soil. Supporters see it as a promising climate solution with co-benefits for soil health, according to a press release.

The study found that basalt raised soil pH by about 0.8 units, improving fertility. It also released key nutrients like potassium, which significantly boosted plant growth in sandy soils. However, uptake of others — including phosphorus and trace metals — decreased in some cases, especially in nutrient-rich soils, due to altered soil chemistry.

“These results show that basalt can be an effective soil amendment, especially on nutrient-poor or slightly acidic soils,” said Rothamsted’s Stephan Haefele who was one of the co-authors of the study. “But there is no universal outcome — local soil characteristics play a crucial role.”

The findings underscore the importance of site-specific assessments before scaling up enhanced weathering. While the approach shows potential for capturing carbon and boosting crop yields, it’s not a one-size-fits-all solution.

This research adds to the growing evidence base supporting rock dust as a tool in regenerative agriculture — a practice gaining traction as a key strategy in the fight against climate change.